Parallel configuration composite material fabricator and related methods

ABSTRACT

The present invention relates to device and methods for fabricating a composite article having a plurality of material dispensers, which can increase productivity. In one embodiment, a device includes a structure defining a work surface datum, and material dispensers movable relative to the structure. Each material dispenser applies strip material to the work surface datum along a predetermined axis. The predetermined axes are generally parallel to one another. The strip material applied to the work surface datum forms a layer of the composite article.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.10/301,949 filed Nov. 22, 2002 now U.S. Pat. No. 7,137,182. Thedisclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to devices and methods for thefabrication of articles from composite materials.

BACKGROUND OF THE INVENTION

Articles that are formed partially or wholly from composite materials(herein after referred to as “composite articles”) are employed in avast number of fields, usually to provide the finished article withdesired characteristics, such as a relatively low weight and arelatively high strength. One method of fabricating composite articlesincludes the use of strips of a composite material, such as a graphitetape or cloth, to form what is known in the art as a composite “lay-up”.The lay-up includes one or more layers, with each layer being formedfrom touching and/or overlapping strips of the material. A resin, whichmay be pre-impregnated in the material or later injected into one ormore of the layers of material, is later processed to cure the lay-upsuch that the material strips are bonded together. Typically, the lay-upis formed on a mandrel having a formed work surface that conforms to thedesired geometry of the finished composite article. Since the lay-up isrelatively flexible and unable to support itself prior to curing, themandrel is usually employed to support the lay-up during the curingprocess.

Known methods for the fabrication of composite articles include manualand automated fabrication. Manual fabrication entails manual cutting andplacement of material by a technician to a surface of the mandrel. Thismethod of fabrication is time consuming and cost intensive, and couldpossibly result in non-uniformity in the lay-up. Known automatedfabrication techniques include: flat tape laminating machines (FTLM) andcontour tape laminating machines (CTLM). Typically, both the FTLM andthe CTLM employ a solitary composite material dispenser that travelsover the work surface onto which the composite material is to beapplied. The composite material is typically laid down a single row (ofcomposite material) at a time to create a layer of a desired width andlength. Additional layers may thereafter be built up onto a prior layerto provide the lay-up with a desired thickness. FTLM's typically applycomposite material to a flat transfer sheet; the transfer sheet andlay-up are subsequently removed from the FTLM and placed onto a mold oron a mandrel. In contrast, CTLM's typically apply composite materialdirectly to the work surface of a mandrel.

The specifications for many composite articles further require that thecomposite material of each layer be applied in a predeterminedorientation, with the orientations of each layer being different. Tovary the orientation of the composite material in the layers, typicallyeither the tape dispenser is moved at different angles relative to themandrel or transfer sheet, or the mandrel or transfer sheet is manuallyshifted relative to the tape dispenser. The batch processing employed inknown automated tape laminating devices can be slow, tedious, andcumbersome. Therefore, there is a need for an automated process thatexpedites the fabrication of and increases the quality of compositelay-ups.

SUMMARY OF THE INVENTION

The present invention relates to device and methods for fabricating acomposite article having a plurality of material dispensers, which canincrease productivity. In one embodiment, a device includes a structuredefining a work surface datum, and material dispensers movable relativeto the structure. Each material dispenser applies strip material to thework surface datum along a predetermined axis. The predetermined axesare generally parallel to one another. The strip material applied to thework surface datum forms a layer of the composite article.

The present invention further provides methods of fabricating acomposite article. In one exemplary implementation, a method generallyincludes providing a plurality of material dispensers, applying stripmaterial with the plurality of material dispensers to a work surfacedatum along a predetermined axis to form a first layer having a firstorientation, wherein the work surface datum is movable relative to theplurality of material dispensers, rotating one of either the worksurface datum or the plurality of material dispensers, and applying thestrip material over the first layer along a predetermined axis to form asecond layer having a second orientation.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples areintended for purposes of illustration only and are not intended to limitthe scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of a composite fabrication deviceconstructed in accordance with a preferred embodiment of the presentinvention;

FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a plan view of a layer of strip material applied to a worksurface datum in accordance with one preferred embodiment of the presentinvention;

FIG. 4A is a schematic illustration showing the fabrication of anexemplary composite lay-up on a mandrel;

FIG. 4B is a schematic illustration showing the fabrication of anexemplary composite lay-up on a transfer sheet;

FIG. 5 is a perspective view of a portion of an exemplary materialdispenser illustrating the cutter and idler drum;

FIG. 6 is a partially broken away plan view of the composite lay-up ofFIG. 1 illustrating the various layers of strip material and theirorientations;

FIG. 7 is a perspective view of a first alternate preferred embodimentof the present invention showing dual support bases in an active and anon-active area and a processing station; and

FIG. 8 is a partial overhead view of a second alternate preferredembodiment of the gantry and material dispenser configuration inaccordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, a composite fabrication device constructed inaccordance with the teachings of the present invention is generallyindicated by the reference numeral 12. In the particular embodimentillustrated, the composite fabrication device 12 includes a structure 14having a work surface datum (i.e., a work surface) 16. The compositefabrication device 12 has a gantry 18 elevated over the work surfacedatum 16. In the example provided, the gantry 18 includes two verticalbeams 20 and a bridge rail 22. Those skilled in the art will appreciate,however, that the gantry 18 may be constructed in numerous other waysincluding a pair of overhead runways or beams (not shown) that supportthe opposite ends of the bridge rail 22.

The vertical beams 20 are associated with a pair of tracks 24 that boundthe opposite sides of a working area 26. For purposes of discussion, thetracks 24 define a X-axis that is generally perpendicular to a Y-axisdefined by the bridge rail 22. The vertical beams 20 preferably movealong the tracks 24, thus the tracks 24 may be, for example, rails overwhich wheels (not shown) attached to the vertical beams 20 travel.Preferably, the gantry 18 is selectively propelled along the tracks 24by a suitable drive mechanism 25, which may be a servo tractor or anydrive mechanism known in the art. The bridge rail 22 is attached to thevertical beams 20, either in a fixed position or such that it hasvertical mobility with respect to the structure 14 below. In the latterinstance, the bridge rail 22 is permitted to move vertically to adjustthe position of the bridge rail 22 relative to the structure 14 that islocated beneath the gantry 18. Translation of the gantry 18 on thetracks 24 and, if the gantry 18 is equipped as such, vertical movementof the bridge rail 22 may be automatically or manually controlled. Thecomposite fabrication device 12 includes a control processing unit, or acontroller 15, that interfaces with the drive mechanism 25 and thegantry 18 and its several components. In view of the extent of thedisclosure, a detailed discussion of the construction and operation ofthe controller 15 need not be provided herein as such controllers 15 arewell within the capabilities of one skilled in the art.

An anterior end 28 and a posterior end 30 of the working area 26 arebounded by end tracks 32. Within the working area 26, the structure 14may be placed upon or incorporated into a support base 34. In apreferred aspect of the present embodiment of the invention, the supportbase 34 is rotatable relative to the bridge rail 22. Such rotation ispreferably achieved by placing the support base 34 on a rotary turntable80 or incorporating a conventional rotary drive mechanism 80 a into thesupport base 34. Thus, the work surface datum 16 of the structure 14 mayhave its orientation changed by rotating the rotary turntable 80 in theexample provided. Alternatively, the support base 34 may have a fixedposition and the gantry 18 may be moved (e.g., rotated) or the movementof the bridge rail 22 rotated and controlled along both the X and Y axesto change the orientation with which material is laid onto the worksurface datum 16 as will be discussed in greater detail below.

A plurality of material dispensers 36 are attached to opposite sides 58and 60, respectively, of the bridge rail 22. The material dispensers 36may also be attached to only a single side (58 or 60) of the bridge rail22, if adjacent material dispensers 36 are oriented to dispense materialin opposite directions. The material dispensers 36 apply material strips62, such as for example, carbon fiber pre-impregnated resin tapes orcloth, to the work surface datum 16 of the structure 14. The position ofmaterial dispensers 36 along the bridge rail 22 is fixed such that thematerial dispensers 36 are attached at predetermined positions along thebridge rail 22. In an alternate embodiment, the position of the materialdispensers 36 may be adjustable and the position of the materialdispensers 36 may be translated relative to one another along the bridgerail 22 to accommodate a variety of differently sized strip materials 62and material dispenser 36 configurations, as shown in FIGS. 1 and 2. Thematerial dispensers 36 may be translated along the bridge rail 22 by anyknown method in the art. One preferred method is to attach the materialdispensers 36 to a track 65 along the bridge rail 22. Locking mechanisms67 on the material dispensers 36 lock the position of each materialdispenser 36 during operation. Release of the locking mechanisms 67allows movement of the material dispensers 36 to new positions along thebridge rail 22. The bridge rail 22 and track 65 may also permitintroduction or removal of material dispensers 36, as necessary.

A preferred configuration for the present embodiment includes staggeredmaterial dispensers 36 on the sides 58, 60 of the bridge rail 22, asshown in the example of FIG. 1. Each material dispenser 36 has a housing52 containing rolled strip material 62. Since the housing 52 typicallyis wider than the width of the strip material 62, the staggeredconfiguration allows applied strip materials 62 to abut or only havesmall gaps (preferably less than one-half the width of strip material62) in between. Thus, a material dispenser 36 on the first side 58 ofthe gantry 18 is situated with respect to a material dispenser 36 on thesecond side 60 so as to allow the strip material 62 to be applied in analternating strip pattern. The amount of distance between edges 71 ofstrip material 62 is a function of the distance between the materialdispensers 36 and is chosen based upon various design criteria for thecomposite lay-up that is to be fabricated. The position of stripmaterial 62 edges 71 relative to one another may range from a small gap(which is preferred) to no overlap (i.e., abutting) to over one-half thewidth of the strip material 62. The distance between the materialdispensers 36 may require adjustment (via the track 65 and lockingmechanisms 67, for example) to provide the desired degree of overlap. Inan alternate embodiment, the material dispensers 36 may be fixed alongthe bridge rail 22, and the bridge rail 22 moves a short distance alongthe Y axis (i.e. less than the width of the strip material 62), toenable similar strip material 62 layers to overlap previously appliedlayers of strip material 62 in the same orientation.

With reference to FIG. 2, material dispensers 36 are illustrated ascoupled to the bridge rail 22. For purposes of discussion, a first one(64) of the material dispensers 36 is coupled to the first side 58 ofthe bridge rail 22, and a second one (66) of the material dispensers 36is coupled to the second side 60. Each of the material dispensers 36operably houses strip material 62 that is rolled onto a spool 90 in thematerial dispenser housing 52. Such strip material 62 on a spool 90 mayoptionally be held in a separate cartridge (not shown) contained withinthe housing 52. Strip material 62 has a backing paper 92 to preventundesirable blocking of the strip material 62 during release. The stripmaterial 62 is cut prior to approaching a release region 94 wherein thestrip material 62 is applied to the work surface datum 16.

The material dispenser 36 also has a cutter 102 for cutting the stripmaterial 62. Such cutters 102 may be for example, blade or lasercutters. One preferred embodiment of a cutter 102 is shown in FIGS. 2and 5, where a cutter drum 104 has a surface 108 with a single cutterblade 106 protruding and extending along the entire length of the cutterdrum 104. As strip material 62 is applied to the work surface datum 16,the blade 106 faces away from the area 110 where strip material 62passes. As the strip material 62 is unrolled, it passes over an idlerdrum 112 which directs it towards a release region 114. The stripmaterial 62 passes between the idler drum 112 on one side and a cutterdrum 104 on the other side. The cutter drum 104 sits stationary with thecutter blade 106 facing away from the strip material 62 passing by,unless a cut in the strip material 62 is necessary. Then, the cutterdrum 104 is actuated and rolls towards the strip material 62 to cut it.This type of cutter drum 104 enables cutting to be accomplishedcontinuously without interrupting strip material 62 application. Thecutter drum 104 is configured such that only the strip material 62 iscut, leaving the backing paper 92 intact. The backing paper 92 continuesto be wound onto a collector spool 116. The collector spool 116 may alsobe optionally contained in a cartridge (not shown) in the housing 52with the roll 90 of strip material 62. The backing paper 92 draws thestrip material 62 into the release region 114 of the material dispenser36. The backing paper 92 facilitates movement and smooth application ofthe strip material 62 along the work surface datum 16.

An alternate embodiment of the cutter drum 104 of the present inventionincludes a helical configuration blade (not shown) that enables angledcuts to be made while the cutter drum 104 rotates towards the stripmaterial 62. When the cutter blades 106 for each material dispenser 36make straight cuts across the strip material 62, the resulting stripmaterial composite lay-up has edges that are serrated or crenulated.Such a composite lay-up can later be trimmed, usually after curingoccurs in the lay-up mandrel, to achieve a straight finished edge forthe finished composite article.

The strip material 62 and backing paper 92 are compressed or smoothedagainst the work surface datum 16 by a primary compactor 96, or shoe,which is retractable (i.e. capable of descending from a bottom surface98 of the material dispenser 36 and also capable of at least partiallyretracting above the bottom surface 98 of the material dispenser 36).Further, the primary compactor 96 optionally has a degree of freedom ofrotational movement as designated by arrow R that enables the primarycompactor 96 to adapt to angles or contours along the work surface datum16. This freedom of movement may be necessary when the structure 14 is acontoured lay-up mandrel. The material dispenser 36 optionally has atrailing compactor 100, which may further assist in smoothing the stripmaterial 62 along the work surface datum 16, especially at terminaledges 74 (FIG. 1) of the strip material 62 after it is cut. Both theprimary and trailing compactors 96, 100 retract when the materialdispenser 36 is not in use and preferably the movements of the primaryand trailing compactors 96, 100 are automated by computerized controls.

Strip materials 62 may include fiber reinforced composites, polymers(e.g. adhesives or laminates), and metal foil, although the presentinvention is not limited to the materials listed above, but rather isadaptable to any strip material. As those skilled in the art willappreciate, material selection for the strip material 62 is dependent onthe application in which the composite article will be used, anddifferent strip materials 62 may be applied in alternate layers toprovide the composite lay-up with desired characteristics.

Fiber reinforced composite materials are generally categorized as tape,woven cloth, non-woven cloth, paper, and mixtures thereof. “Tape”generally refers to uniaxial reinforcement fibers that extend along asingle axis of the strip material. The term “cloth” generally refers toreinforcement fibers laid along at least two different axes within thestrip material. Cloth is commercially available as bi-axial, tri-axialand quad-axial, indicating fibers extending in two, three, or fourdifferent axes, respectively. The fibers may optionally be woven withone another, or may be manufactured as non-woven cloth. A vast array ofcomposite reinforcement fibers are commercially available, such as forexample, carbon, Kevlar® fibers, glass, and mixtures thereof. Metalfoils are also known in the art, and may be included in compositearticles. Such metal foils are frequently interspersed as materiallayers within the lay-up composite. Strip materials are commerciallyavailable in a wide variety of widths. One common width for fiberreinforced material strips is 6 inches. The present inventioncontemplates and is adaptable to a variety of strip material widths, andmaterial dispensers 36 may be re-positioned along the gantry 18 toaccommodate different strip material widths.

The term “composite article” generally refers to a material thatincludes a composite resin matrix, wherein the resin includes at leastone polymer or mixtures of polymers, and fibers or particles that aredistributed throughout to form the matrix or composite. Strip material62 is available in both resin pre-impregnated and non-impregnatedconfigurations. A pre-impregnated resin strip material 62 (generallyreferred to as “pre-preg”) has resin added into the strip prior tospooling it onto rolls. When a non-impregnated strip material 62(generally referred to as “dry fiber”) is employed, a resin is typicallyadded in a subsequent processing step. Non-impregnated strip materials62 typically employ a tackifier or adhesive (typically a polymer) thatfacilitates adhesion of the strip material 62 layers to the work surfacedatum 16 or other previously applied layers of strip material 62.Processing methods that subsequently add the resin into the layers ofstrip material 62 are well known in the art and include, for example,vacuum assisted resin infusion into the strip material 62.

Returning to FIG. 1, the material dispensers 36 must be changed out whenthe strip material 62 supply is exhausted or a different layer of stripmaterial 62 is needed for the composite lay-up. In the particularembodiment provided, material changers 40 service the materialdispensers 36 to replace the entire material dispenser 36 itself. Thematerial changers 40 may optionally change only material cartridges (notshown) contained within the housing 52 of the material dispensers 36.Thus, it is contemplated that the material changers 40 may optionallychange out the entire material dispenser 36, including a housing 52, ormay change out only a material cartridge leaving the housing 52 andmaterial dispenser 36 attached to the bridge rail 22. The example shownin FIGS. 1 and 2 depicts material changers 40 that replace the entirematerial dispenser 36. However, either configuration of material changer40 is feasible and contemplated in the present invention.

In a preferred embodiment, one or more mobile modular material changers40 translate along each of the end tracks 32 to service the plurality ofmaterial dispensers 36 that are located on an associated side of thebridge rail 22. The end tracks 32 are adjacent to changing stations 38which service the mobile material changers 40 and provide a repositoryfor used and new material dispensers 36. The mobile modular materialchangers 40 hold a replacement material dispenser 36 for replenishing orchanging the strip material 62 in the material dispensers 36 attached tothe gantry 18.

Preferably the mobile modular material changer 40 is automated andinterfaces with the gantry 18 to replace a designated material dispenser36 when, for example, the material in a given material dispenser 36 hasdiminished to a predetermined level or a different strip material 62 isto be applied. The gantry 18 is moved to either the anterior orposterior end 28, 30 so it is next to the end track 32. The materialchanger 40 moves laterally along the end track 32 so that it approachesthe individual material dispenser 36 requiring service. Such a materialdispenser 36 may be selected based on an output signal from the materialdispenser 36 itself indicating that the amount of strip material 62 islow or may be automatically or manually selected to change the stripmaterial 62 within the composite lay-up being formed. The materialchanger 40 has a receiving region 54 to place a spent or used materialdispenser 36 into. The material changer 40 also has a replacement region56, storing the material dispenser 36 so that it is available forplacing into the material dispenser 36.

The material changer 40 engages the material dispenser 36, interfaceswith the gantry 18 as necessary to release the quick connect 68 which iseither interconnected directly with the bridge rail 22 (not shown) oralternately with the track 65 and locking mechanism 67, and removes thematerial dispenser 36. The material changer 40 places the “old” materialdispenser 36 into the receiving region 54, and acquires a “new” materialdispenser 36 which it attaches to the bridge rail 22. Alternately, thematerial replenishing and/or changing operation may be accomplishedmanually. In such an embodiment, changing stations 38 and end tracks 32would not be necessary components.

The material dispensers 36 are attached either directly to the chairrail 22, or attached to the track 65 on the chair rail 22, via acoupling 68. One preferred type of coupling 68 is a quick releaseconnection generally known as a “quick connect”, such as a Quick Change300, which is commercially available from EOA Systems, Inc., located inCarrollton, Tex. Further, if only a cartridge (not shown) is removedfrom the material dispenser 36, it preferably is coupled to the housing52 by a quick connect. As those skilled in the art will appreciate,however, suitable couplings and quick connects are well known in the artand as such, the scope of the present invention is not limited to theexemplary coupling discussed and illustrated herein. If the first andsecond material dispensers 64, 66 are attached to the track 65 thatpermits movement of the material dispensers 64, 66 along the bridge rail22, the releasable locking mechanism 67 locks the material dispensers 36in place.

As shown generally in FIGS. 1 and 2, each of the first and secondmaterial dispensers 64, 66 is employed to apply a strip material 62 tothe work surface datum 16 of the structure 14. A pattern of multiplematerial strips 62 applied onto the work surface datum 16 by theplurality of material dispensers 36 on the first and second sides 58, 60of the bridge rail 22 form a layer 82. An out stroke of the bridge rail22 from the starting point 81 to the ending point 83 enables thematerial dispensers 36 to apply strip material 62 in a first direction70, where each material strip 62 is substantially parallel with oneanother. The return or back stroke that occurs as the bridge rail 22travels in a reverse direction from the ending point 83 back to thestarting point 81 also enables strip material 62 to be laid in parallelalong a predetermined axis by the second material dispensers, as shownby 72. A single round trip stroke of the gantry 18 creates an entirelayer of material 82 composed of material strips 62 all parallel withone another.

The gantry 18 moves across the working area 26 over the structure 14 ina first direction 70 (i.e., an out stroke) and returns in a seconddirection 72 (i.e., a return stroke) laying strip material 62 along apredetermined axis. Although the gantry 18 may move over the entireworking area 26 which spans from the anterior to posterior ends 28, 30,the gantry 18 may alternatively only move over small regions of theworking area 26. Thus, during operation when strip material 62 is beingapplied, the gantry 18 is capable of traveling a shortened distancealong the tracks 24. This is advantageous where a structure 14 and itswork surface datum 16 are relatively small in comparison to the overallwork area 26 and the gantry 18 may only need to move partially along thetracks 24 from a starting position, or point, 81 at the front of thestructure 14 to an ending position, or point, 83 at the end of thestructure 14. Partial translation of the gantry 18 along the tracks 24facilitates faster application of strip material 62 along apre-determined axis to the work surface datum 16.

With reference to FIG. 3, in the particular configuration illustrated,strip material 62 is applied in a first direction 70 (via the firstmaterial dispensers 64 in FIG. 2 and a second direction 72 (via thesecond material dispensers 66 in FIG. 2), wherein the second direction72 is opposite the first direction 70. Each edge 71 of strip material 62interfaces with (i.e. comes into close proximity with by either having asmall gap or abutting) another edge 71 of another strip material 62 thatwas applied in the opposite direction. The junction lines 75, 77indicate where the edges of strip material 62 applied in a firstdirection 70 approach and/or abut the edges of the strip material 62applied in a second direction 72.

With reference to FIGS. 4A and 4B various alternatively constructedstructures 14 are illustrated. The structure 14 shown in FIG. 4A is alay-up mandrel 87. The lay-up mandrel 87 may be a template or mold thatdefines the work surface datum 16 onto which the strip material 62 islaid. Preferable, the work datum surface 16 of the lay-up mandrel 87 hasonly slight to moderate contours, such that the primary compactor 96 andtrailing compactor 100 can pivot at slight to moderate angles to followthe contour in a manner such that the strip material is smoothed againstthe work surface datum 16. Typically a maximum grade or angle thecompactors 96,100 can accommodate is about a 15% incline. After thestrip material 62 application is complete (i.e., all of the layers havebeen laid onto the work surface datum 16 to thereby form a compositematerial lay-up 91), the lay-up mandrel 87 is removed from the workingarea 26 (FIG. 1) and further processed. For example, further processingmay include adding polymer resin to the composite material lay-up 91through vacuum injection processing and/or curing or cross-linking thestrip material 62 that makes up the composite material lay-up 91 throughautoclaving or baking. After processing, the composite article (notshown) is removed from the lay-up mandrel 87, where it may be trimmedand/or machined as necessary.

The structure 14 shown in FIG. 4B is a transfer sheet 89, which is alayer of material that provides a surface on which to apply stripmaterial 62. As with a lay-up mandrel 87 shown in FIG. 4A, the stripmaterial 62 is applied in multiple layers to form a lay-up 91 on thetransfer sheet 89. After application of the strip material lay-up 91 iscompleted, the transfer sheet 89 is transferred to a separate lay-upmandrel (not shown) having the desired contour for the composite articleand the strip material lay-up 91 is cured. The transfer sheet 89 may bedesigned to be removed from the lay-up 91, such as, for example, aremovable paper backing as is known in the art. The transfer sheet 89may alternatively be incorporated into the composite article or a part,forming, for example, an exterior or interior surface of the compositearticle. Incorporated transfer sheets 89 may be, for example, scrimcloth or fiberglass cloth, which may have later advantages if thecomposite part is machined. For example, the incorporated transfer sheet89 may protect against splintering of the cured composite article whenit is subjected to drilling or machining, and further may provide asmoother exterior finish. Subsequent processing of the lay-up 91, withor without the transfer sheet 89 is similar to the processing of thelay-up 91 when the mandrel 87 in FIG. 4A is used as the structure 14.

With renewed reference to FIG. 1, one aspect of a preferred embodimentof the present invention includes the support base 34, preferablymounted on the rotary turntable 80, wherein the orientation of the stripmaterial 62 forming a layer 82 as applied to the work surface datum 16can be selectively changed between layers 82 of the strip material 62.Composite reinforced materials having a single reinforced fiberdirection (e.g. uniaxial tape) exhibit anisotropic characteristics,meaning that they typically exhibit relatively high strength along theprimary axis of the reinforcement fibers, but do not exhibit the samestrength along other axes. Thus, depending on the selection of stripmaterials and the application in which the composite reinforced materialis used, it may be necessary for the composite material to exhibitisotropic or uniform strength in multiple directions for severalpredetermined axes. As discussed previously, when multiple materiallayers are laid upon the work surface datum 16 they are generallyreferred to as “lay-up”. When the support base 34 is rotated betweenmaterial layers 82, the lay-up has different orientations, such as thecomposite material shown in FIG. 6.

In the particular example provided in FIG. 6, a first layer 84comprising multiple material strips 62 applied to the work surface datum16 each laid along an axis that is parallel to a first predeterminedaxis A are formed by movement of the bridge rail 22 along the X axis. Asecond layer 86 of strip material 62 is applied over the first layer 84such that each of the strips 62 are applied along an axis that isparallel to a second predetermined axis B, which is rotated at +45° fromaxis A. To accommodate this change, the support base 34 is rotatedcounter-clockwise 45° from the 0° position. A third layer 88 of stripmaterial 62 is applied over the second layer 86, such that each of thestrips are applied along an axis that is parallel to a thirdpredetermined axis C, which is rotated −45° from axis A. To accommodatethis change, the support base 34 is rotated clockwise 45° from the 0°position (i.e., 90° clockwise from the +45° position). The location ofthe 0° position relative to the work surface datum 16 is established bythe specifications for the composite article. In one preferredembodiment of the present invention, the rotary turntable 80 isautomated via the conventional rotary drive mechanism 80 a, of the typethat is well known in the art. The operation of the rotary turntable 80a is integrated with the application of strip material 62 from thematerial dispensers 36. Further, as recognized by one of skill in theart, various configurations and angles may be selected for a compositematerial lay-up 91. As such, the above example is not intended to limitthe scope of the invention.

Multiple layers of the strip material applied over the work surfacedatum 16 (i.e. the composite material lay-up 91) can have layers 82 ofstrip material 62 ranging from four to over one-hundred. In onepreferred embodiment of the present invention, the strip material 62 hasa width of 6 inches and creates a swath of material strips 62 having anoverall width of approximately 15 feet (where there are 15 materialdispensers on each side of the gantry 18 or 30 total including bothsides). A preferred range for the number of layers 82 for the lay-up 91is between about 20 and 40 layers.

In FIG. 7, an alternately constructed composite fabrication device 12′is illustrated, wherein the material dispensers 36 apply strip material62 to at least two structures 124 having work surface datums 16 a′ and16 b′. The several components of the composite fabrication device 12′(e.g., material changers 158, etc.) are controlled similarly to thosedescribed in previous embodiments by a controller 15′. A first andsecond structure 128 and 130, respectively, rest on a first support base132 within the work area 134, in an active area 144. A non-active area145 within the work area 134 is identically configured to the activearea 144 above, and has a third and fourth structure 136 and 138,respectively, resting on a second support base 140. An overhead gantry18′ configuration is the same structurally and operably as thosedescribed in previous embodiments, and has a plurality of materialdispensers 36 that apply strip material 62 to the work surface datums 16a′, 16 b′. The gantry 18′ applies strip material 62 to the first andsecond structures 128,130 on the first support base 132 in active area144. The second support base 140 with the third and fourth structures136,138 are in the non-active area 145, where the gantry 18′ is notoperating overhead. This embodiment permits two separate working areas144,145 for the gantry 18′ and material dispensers 36. Thus, while thegantry 18′ is working over the first support base 132, the secondsupport base 140 may be accessed for other activities aside from stripmaterial application. This configuration is particularly advantageouswhere the structure 124 has lay-up applied (e.g. the transfer sheet orlay-up mandrel itself) and must be transferred to another station forfurther processing.

As shown in FIG. 7, the structures 124 are two separate transfer sheets,a third and fourth transfer sheet 136 and 138, which are placed on thesecond support base 140. The third and fourth transfer sheets 136, 138are transferred and placed on a lay-up mandrel 152 (for simplicity onlya single lay-up mandrel is depicted in FIG. 7). The lay-up mandrel 152is then cured or cross-linked in a processing chamber 154. Such aprocessing chamber 154 is typically a heat oven or an autoclave chamber.The configuration of multiple support bases 132, 140 in the presentembodiment permits continuous material dispenser 36 application andincreases work efficiency over a single support base (132 or 140), whereoperations must be ceased to remove and place a new structure 124 ontothe support base (132 or 140).

FIG. 8 is a partial overhead view of a composite fabrication device 12″constructed in accordance with the teachings of a second alternateembodiment of the present invention. The composite fabrication device12″ includes a gantry 18″ having four vertical beams 20″, a pair ofspaced apart bridge rails 22″, a pair of lateral stabilizers 300 and arotary dispensing unit 302 that is suspended from the bridge rails 22″.Each bridge rail 22″ is coupled to a pair of the vertical beams 20″ andeach lateral stabilizer 300 is coupled to a pair of vertical beams 20″.The gantry 18″ is movable on the tracks 24 in a manner that is similarto that described above for the embodiment of FIG. 1.

The rotary dispensing unit 302 includes an arcuate outer track 308 and arail 310 to which the material dispensers 36 are mounted. The rail 310may be similar to the track 65 (FIGS. 1 and 2), and the materialdispensers 36 are removably and adjustably coupled to the rail 310through conventional quick connects 68 in a manner similar to that whichis described above. The bridge rails 22″ support the outer track 308 forrotation thereon, with the rotation of the outer track 308 beingcontrolled via a conventional and well known rotary drive mechanism 320.The rail 310 is fixed to the outer track 308. Alternately, the outertrack 308 may be non-rotatably supported by the bridge rails 22″ and therail 310 rotatably coupled to the outer track 308.

A linear drive mechanism 322 is further provided to control the movementof the rotary dispensing unit 302 along the Y axis on the bridge rails22″. The linear drive mechanism 322, rotary drive mechanism 320, anddrive mechanism 25 are preferably coordinated by a controller 15″ sothat the axis 332 of the rotary dispensing unit 302 may be accuratelypositioned rotationally and thereafter moved in the X and Y directionsto dispense strip material 62 into the work surface datum 16 along adesired axis.

In the particular embodiment illustrated, a first layer 330 was appliedwith the rotary dispensing unit 302 in a 0° orientation. Then, therotary dispensing unit 302 was rotated clockwise to a −45° angle withrespect to the 0° axis reference, and the gantry 18″ traveled along theX and Y directions to apply a second layer. As appreciated by one ofskill in the art, the gantry 18″ may travel only partially along thetracks 24 to apply strip material 62 at an angle, rather than fullstrokes from one end to the other. Preferably, due to the highlysynchronized movements required in the present invention, the presentembodiment is fully automated with computerized control systems. Otheraspects of the present invention are similar to those previouslydescribed, such as automatic material replacement.

The present invention further provides methods for forming compositecontaining materials according to the teachings of the preferredembodiments of the present invention. A method for fabricating acomposite article includes the steps of providing a plurality ofmaterial dispensers 36, where each of the material dispensers 36dispenses a strip material 62 to a work surface datum 16 on a structure14 beneath the material dispensers 36. Then the strip material 62 isapplied to a work surface datum 16, wherein each of the materialdispensers 36 applies strip material 62 along a predetermined axis ontothe work surface datum 16 to form a first layer 84 having a firstorientation, wherein the work surface datum 16 is movable relative tothe plurality of material dispensers 36, or in the alternative, whereinthe plurality of material dispensers 36 are movable relative to the worksurface datum 16. Next, either the work surface datum 16 or theplurality of material dispensers 36 are rotated, and then strip material62 is applied over the first layer 84 along a predetermined axis to forma second layer 86 having a second orientation. Such a process may berepeated to apply multiple layers 82. The strip material 62 can be cutby a cutting device 102 prior to the rotation step. A treatment step mayfollow the application of the layers 82 of strip material 62 to the worksurface datum 16, where the layers 82 are cured or reacted. Further, theplurality of material dispensers 36 can be automatically changed withmaterial dispenser changers 40.

While the invention has been described in the specification andillustrated in the drawings with reference to a preferred embodiment, itwill be understood by those skilled in the art that various changes maybe made and equivalents may be substituted for elements thereof withoutdeparting from the scope of the invention as defined in the claims. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiments illustrated by the drawingsand described in the specification as the best mode presentlycontemplated for carrying out this invention, but that the inventionwill include any embodiments falling within the foregoing descriptionand the appended claims.

What is claimed is:
 1. A method for fabricating a composite article witha plurality of composite material dispensers, the method comprising:installing an independent supply roll of composite strip materialonboard each of the composite material dispensers; based at least inpart on a dimension of the composite strip material, selectively spacingthe material dispensers on two opposite sides of a bridge rail to whichthe dispensers are adjustably coupled, the bridge rail thus extendingbetween, and supporting, a first plurality of material dispensers and asecond plurality of material dispensers, the first and secondpluralities of material dispensers configured relative to one anothersuch that the first and second pluralities of material dispensersdispense the composite strip material in opposite directions relative tothe bridge rail; moving the bridge rail in a first direction to applythe composite strip material from the first plurality of materialdispensers during a first stroke, where the first direction is toward afirst of the opposite sides of the bridge rail; moving the bridge railin a second direction to apply the composite strip material from theplurality of second material dispensers during a second stroke, wherethe second direction is toward the second of the opposite sides; furthermoving the bridge rail pivotally about an axis perpendicular to alongitudinal axis of the bridge rail, to collectively rotate all of thefirst and second pluralities of material dispensers, the rotation beingperformed either subsequent to the first stroke or subsequent to thesecond stroke, and then stopping movement of the bridge rail relative tothe work datum before applying the composite strip material from one ofthe first or second pluralities of material dispensers in a subsequentstroke; and the composite strip material forming at least a first layerof the composite article having the composite material oriented in afirst orientation and, a second layer of the composite material of thecomposite article having a second orientation which is not parallel tothe first layer.
 2. The method of claim 1, comprising maintaining atleast one of the first and second material dispensers in an inactivestate while another of said first and second material dispensers isapplying strip material from its onboard supply of strip material. 3.The method of claim 1, wherein the second stroke is performed only aftercompletion of the first stroke.
 4. The method according to claim 3,comprising moving at least one of the first and second pluralities ofmaterial dispensers transversely relative to an axis representing thefirst and second strokes.
 5. The method according to claim 1, furthercomprising replenishing the supply rolls of strip material onboard thefirst and second pluralities of material dispensers by using a pluralityof automated material dispenser changers disposed on opposite sides ofthe bridge rail.
 6. The method according to claim 1, further comprisingsmoothing strip material by using retractable compactors onboard thefirst and second pluralities of material dispensers.
 7. A method forfabricating a composite article with a plurality of material dispensers,the method comprising: supporting a bridge rail for rotational movement;applying along a first axis first composite strip material from only afirst plurality of material dispensers to a work surface datum duringlinear movement, in a first direction, of the bridge rail to which thefirst plurality of material dispensers is attached, and second compositestrip material from a second plurality of material dispensers to thework surface datum during linear movement, in a second direction alongthe first axis, of the bridge rail to which the second plurality ofmaterial dispensers is attached, the first and second materialdispensers attached to sides of the bridge rail that face the dispensingdirections, the first and second material dispensers extending generallyin the opposed dispensing directions from the opposite sides of thebridge rail; applying the second composite strip material from thesecond material dispenser to the work surface datum along a second axisnon-parallel to the first axis during only movement of the bridge railin a second direction; rotating the bridge rail about an axis that isperpendicular to a longitudinal axis of the bridge rail to collectivelyand simultaneously rotate all of the first and second pluralities ofmaterial dispensers, and then stopping rotation of the bridge rail, andthen further applying the composite strip material from one of saidfirst and second material dispensers; and the first and second stripmaterials forming one or more layers of the composite article that arearranged non-parallel to one another.
 8. The method of claim 7, wherein:the first material dispenser is moved in a first stroke of movement asthe first strip material is dispensed from the first material dispenser;and the second material dispenser is moved in a second stroke ofmovement as the second strip material is dispensed from the secondmaterial dispenser.